Improvement in sand and gravel heaters



J. McC. PERKINS, SAND AND GRAVEL HEATER. No.1'70,894. Patented Dec.7,1875.

INVENTOR.

N. PETERS, PHOTO-LITROGRAPMER, WASHINGTON. D C.

Un'rrnn STATES PATENT OFFICE.

JOHN MGGLARY PERKINS, OF WASHINGTON, DISTRICT OF COLUMBIA.

IMPROVEMENT IN SAND AND GRAVEI. HEATERS.

Specification forming part of Letters Patent No. 170,S94, dated December7, 1875; application filed December 4, 1875.

To all whom it may concern:

Be it known that I, JOHN MOOLARY PER- KINS, of the city of Washington,in the county of Washington and District of Columbia, have inventedcertain new and useful Improvements in Sand and Gravel Heaters; and 1 dohereby declare that the following is a full, clear, and exactdescription thereof, that will enable others skilled in the art to whichit appertains to make and use the same, reference being had to theaccompanying drawings, and to the letters and figures of referencemarked thereon, which form a part of this specification.

The same letters and figures of reference are used to indicate thecorresponding parts.

After describing the invention, its nature and extent will be shown inthe claims.

The object of my invention is to furnish an improved sand and gravelheater, more efficient and simple than those in common use.

In order to fully understand the nature of my invention, I will firstdescribe the defects of the machines of this character now in common usefor the purpose of heating the sand and gravel tb be used in themanufacture of concrete for streetjpavements. One is-a long horizontalcylinder, inside of which a shaft revolves, and by suitable devicescarries the sand or gravel from one end of the cylindrical chamber tothe other end, where it slowly drops on the ground. This machine isquite expensive to buy and to run, and performs, comparatively, littlework. While it may be asuccess as a coffee-roaster, it is a markedfailure as a sand-heater. The other machine is an old form of a drier,which has been used for drying grain and other materials. It consists ofa sand-chamber, whose walls are two perforated cylinders, one cylinderbeing placed within the other. The inner cylinder has a solid conicaltop, from which the sand or gravel slides into the annular chamber. Theouter cylinder is provided with a flaring collar at the top, forming asort of basin to hold the sand there ready to fall into the chamberbelow. Within the inside cylinder is the firechamber, the fire-pot beingsimply the bottom of the chamber provided with an ordinary fire-grate.

, Now, the desirable result sought for in a sand or gravel heater is tokeep the sandchamber surrounded on all sides with hot air at the highestpossible temperature.

The machine last described is much more efiicient and simpler than theone first described; but it has several very material and importantdefects. All the smoke and products of combustion are forced to escapethrough the superincumbent sand. This lessens the heat of thefire-chamber. Then the twolcylinders forming the sand-chamber haveparallel sides, and a series of chambers are frequently formed withthesandchamber, on account of the wet sand adhering to the sides of thechamher in its descent.

Another and a very'serious evil is the comparatively low temperature ofthe outside cylinder, in consequence of its exposure to the directblasts of cold air.

I will now describe my invention, and then state its special advantages.

Figure l is a front view of my invention with the hot-air jacketremoved. Fig. 2 is a view with the jacket 'in place, the top beingbroken away. Fig. 3 is a vertical sectional view taken through thecenter; and Fig. 4 is a front view ofthe top of the fire-chamber,showing its cover and the smoke-pipe.

A is the hot-air jacket; B, the hot-air chamber; D, the sand-chamber; Oand E, the outer and inner walls of the sand-chamber, both of which areperforated to admit hot air for the purpose of driving away the escapingsteam from the drying sand. These perforations may be either in the formof an oblong horizontal slot, or they may be small circular openings; orthey may be made with a downward angle in the'direction of the fallingsand, if desired. The slots at right angles with the cylindrical wallsare preferred, however, because of the lesser difliculty in themanufacture of the cylinders in this manner. The oblique slots have noadvantage in confining the sand in its cham her, as the sand to be driedis damp and wet, and neither escapes into the fire-chamber nor thehot-air chamber, whatever form of slots is made. Indeed, the sand, inactual practice, must be forced down with a rammer by a man at the topof the sand-chamber, standing on an elevated platform made there. Thesand is carried to this platform by an inclined plane connectedtherewith. Fris the hot-air chamher, extending the whole length of theslotted cylinder E. This cylinder rests on the ground, and is providedwith a grate and a door, a. The bottom of this cylinder constitutes thefire-pot. At the top of the fire-chamber is a conical cover, with noperforations or slots. (Shown by H.) At the apex of this cone the smallremovable smoke-pipe is placed, being provided with a damper, e. Theflange f holds the pipe on the top of the cone or cover H. O is madewith its sides tapering, the smaller diameter beingat the top and thelarger at or the, bottom. It stands on legs, and is raised from theground, so that its bottom perimeter is about on a level with the top ofthe door to the fire-pot. Its top is provided with a flaring flange orcollar, G. The hot-air jacket is shown by A, and is provided at its topwith slots for the exit of air laden with vapor from the heated sand.These slots may be open or closed by any of the common forms of dampers.

The operation of drying the sand is now obvious. v

The advantages of my invention are, that the perforated cylinder,enlarged at thebottom, allows the sand to descend without difficulty;The smoke-pipe allows the smoke, &c.,

I to pass oft, after which the damper is closed.

The hot-air jacket keeps the outside perforated tapering cylinder withits surrounding air at a high temperature. All these advantages tend toone common result-namely, to keep' ground to allow the removal of thefalling sand, and provided with a flaring collar, substantially asdescribed, and for the purposes set forth.

2. The combination of the hot-air jacket, elevated from the ground, asshown, and provided with perforations or slots near its top, and fittingclosely to the top perimeter of the flange G, with the taperingperforated cylinder 0, perforated cylinder E, cover H, and smoke-pipe d,substantiallyas described, and for the purposes set forth.

In testimony that I claim the foregoing I have hereunto set my hand this4th day of December, 1875.

JOHN MGOLARY PERKINS.

Witnesses:

ULYssEs G. WHITE, THOMAS C. CoNNoLLY.

